The proposed project is an investigation of catecholamine-containing and serotonin-containing nuclei in the amphibian brain. The purpose of the investigation is twofold: 1. To define the types of cells containing amines and their connections. Thus far one of the cell types appears to be more closely related to chromaffin cells than to neurons. The status of the other two is not yet clear. 2. To determine the functional roles of these nuclei in the normal adult brain and in the developing brain. The methods used will be cytological including ultrastructural and fluorescence histochemical studies of these cells at different stages of development. Experimental procedures will include studies of the effects of exogenous hormones on the cells as well as the effects on presumed target cells of pharmacological treatments resulting in diminution in the amine content of these nuclei.